Do carbohydrates lead to obesity?

No, overeating and no exercise lead to obesity.

Obesity is a very complex behavior, biological and social phenomenon. However it is still true that if you consume more calories than you burn, you will gain weight. It you burn more calories than you consume you will loose weight. The form those calories take fat, carbohydrate and protein are not particularly important regarding weight loss and gain. However, a health balance of nutrients is necessary for overall health.
carbohydrate is either burnt for energy or stored as fat which leads to obesity, no carbohydrates are wasted or excreted. This is why u have to burn more energy than u eat
Excess carbohydrate intake can lead to obesity, but excessive intake of any food can lead to obesity. The simplest answer is that weight gain comes from more calories being taken in than is being used. That is, if you're eating 4000 calories a day and you're only burning off 1700 calories a day, then a lot of those excess calories will get stored away. So the only way to lose weight (short of surgery or liposuction to physically remove the fat) is to either decrease the amount of calories coming in (eat less) and/or increase the amount of calories that your body uses (by exercising).